1. Field of the Invention
The present invention is broadly concerned with dye-supplemented acidic surface cleaning concentrates having excellent long-term stabilities and which can be diluted for use in cleaning surfaces and to detect residual soils, especially proteinaceous soils on such surfaces. More particularly, the invention pertains to such concentrates and use solutions which are strongly acidic and useful for removing insoluble mineral deposits and other acid soluble films from food processing or other equipment, and, by virtue of the stable dye therein, simultaneously provide a visual indication of the effectiveness of the cleaning process. In practice, the solutions hereof may be used in the fashion of normal high acid surface cleaners, and also provide a desirable color indication if significant soil remains on the cleaned surfaces.
2. Description of the Prior Art
Food processors such as dairies regularly clean their processing equipment to insure the cleanliness thereof. In the case of dairies for example, the stainless steel and other metallic processing equipment is subject to the build-up of insoluble mineral deposits such as carbonates or "milk stone." Therefore, in order to prevent unsanitary conditions, dairies routinely clean their processing equipment in a multiple-step operation involving detergents, water softeners and alkalies, with a final clean-up using inorganic acid cleaning solutions. These acidic compositions are normally provided in the form of concentrates containing from about 10%-50% strong acid and are diluted on-site with from about 50-1,500 parts tap water to provide use solutions having a pH of up to about 4. The diluted use solutions are then passed through the processing equipment in order to properly clean the equipment.
Despite these stringent precautions, build-up of various proteinaceous and fat-containing soils on food processing equipment has been known to occur. This is a very serious problem indeed, and can lead to the production and sale of unsafe food products owing to contamination thereof by residual soils that may harbor bacteria on the processing equipment.
It would therefore be a decided advantage to provide, as a part of otherwise conventional acid clean-up concentrates and use solutions, a staining dye sensitive to proteinaceous soils, thereby allowing visual confirmation of whether or not the total clean-up has been successful.